DEVICE FOR THE TRANSMISSION OF KINETIC ENERGY FROM A WORKING FLUID TO A RECEIVING FLUID

Abstract

A system for exchanging heat from a working fluid to a receiving fluid, which includes: a device for transmitting kinetic energy from a working fluid to a receiving fluid, the device including: a circulator suitable for circulating the receiving fluid; a turbine suitable for being driven by the circulation of the working fluid; and a shaft coupling the turbine to the circulator; a heat transfer system for transferring heat from the working fluid by heat transfer from the receiving fluid; and a mixing system for mixing the receiving fluid and the heated working fluid.

Claims

1. A system for exchanging heat from a working fluid to a receiving fluid, said system comprising: a device configured to transmit kinetic energy from a working fluid to a receiving fluid comprising: a circulator configured to circulate the receiving fluid; a turbine configured to be driven by the circulation of the working fluid; and a shaft coupling the turbine to the circulator; a heat transfer system configured to transfer heat from the working fluid by heat transfer to the receiving fluid; a first mixing system configured to mix the receiving fluid and the heated working fluid.

2. The system according to claim 1, further comprising a first pipe configured to circulate the working fluid and connected to the turbine; a second pipe configured to circulate the receiving fluid and connected to the circulator.

3. The system according to claim 1, wherein the first mixing system comprises a first inlet connected to a storage system configured to store the receiving fluid and a second inlet connected to the heat transfer system configured to transfer heat from the working fluid.

4. The system according to claim 1, further comprising a second mixing system configured to mix the fluid coming out of the first mixing system and the heated working fluid.

5. The system according to claim 1, wherein the circulator comprises an outlet to be connected to a hot water storage tank.

6. The system according to claim 1, wherein the first mixing system is a thermostatic valve.

7. The system according to claim 1, wherein the heat transfer system configured to transfer heat is a plate exchanger.

8. The system according to claim 1, wherein: the turbine comprises a first axis of rotation; the circulator comprises a second axis of rotation co-linear with the first axis of rotation; and wherein the shaft couples the first axis of rotation to the second axis of rotation.

9. The system according to claim 1, wherein the turbine is a propeller turbine.

10. The system according to claim 1, wherein the circulator is of centrifugal force vane type.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0044] Other characteristics and advantages of the invention will become clear on reading the description that follows, with reference to the appended figures, which illustrate:

[0045] FIG. 1, a view of a system for the production of domestic hot water according to a first prior art;

[0046] FIG. 2, a view of a system for the production of domestic hot water according to a second prior art;

[0047] FIG. 3, a view of a system for the production of domestic hot water according to one embodiment of the invention;

[0048] FIG. 4, a view of a system for the production of domestic hot water according to another embodiment of the invention.

[0049] For greater clarity, identical or similar elements are marked by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0050] In FIG. 3 is illustrated a system for the production of domestic hot water comprising a device 7 for setting in motion a receiving fluid 4. The device 7 comprises in this exemplary embodiment a first pipe 8 connected to a Kaplan type propeller turbine 71, a second pipe 9 connected to a circulator 72 of centrifugal force vane type and a mechanical shaft 73 mechanically coupling the turbine to the circulator. Thus, when the turbine enters into movement, it drives the circulator. The propeller turbine, in this exemplary embodiment, is connected to the first pipe 8. The circulator, in this exemplary embodiment, is connected to the second pipe 9. Thus, the working fluid circulates in the first pipe 8 and in the turbine 71 and the receiving fluid circulates in the second pipe 9 and in the circulator.

[0051] The propeller turbine 71 is connected at the inlet to the circuit of cold water coming from the drinking water network. The working fluid 1 that can drive the turbine is, in this example, cold water.

[0052] The circulator 72 is connected at the outlet to a hot water storage tank 3, for example a hot water cylinder.

[0053] The receiving fluid 4 going through the circulator is, in this example, hot water coming from the cylinder.

[0054] When domestic hot water is drawn, requiring cooling of the hot water 4 contained in the storage tank 3, the working fluid 1, here cold water, is going to flow through the turbine part 71 of the device 7. The flow of the working fluid 1 through the turbine rotationally drives the turbine 71 on account of the sufficient pressure of the water network. Due to the mechanical coupling by means of the mechanical shaft 73, the gravitational potential energy or kinetic energy of the cold water that goes through the turbine is transformed into mechanical energy at the level of the device 7 and the receiving fluid 4 going through the circulator is driven in movement when the turbine is driven in rotation by the circulation of the working fluid 1.

[0055] The receiving fluid 4 goes through a means 21 for transferring heat from the working fluid, here plate exchanger 21, then the circulator 72 when it is driven in movement. At the outlet of the circulator, this fluid will be called receiving fluid 4a. The working fluid, during drawing, passes through the turbine 71 then the means 21 for transferring heat. The heat of the receiving fluid 4 is transmitted to the working fluid 1 within the plate exchanger. At the outlet of the circulator 72, the receiving fluid 4a is sent back to the storage cylinder 3. The preheated working fluid 11 is sent to the inlet of a means for mixing, of thermostatic valve type for example, in which it is mixed with the fluid coming out of the storage cylinder 3, hereafter called hot water 4b, in order to obtain at the outlet of the means for mixing a third fluid 6 (mixing of the fluid 11 and the fluid 4b) at a temperature enabling its drawing and its use by users. Hence, the more the preheated fluid 11 heats up, the less fluid 4b is consumed to ensure the set point temperature of the fluid 6. This thus makes it possible to reduce the consumption of the fluid 4b, which represents the interest of the system.

[0056] The means 5 for mixing comprises a first inlet 51 connected to the storage means 3 for receiving the receiving fluid 4b and a second inlet 52 connected to the means 21 for transferring heat for receiving the preheated working fluid 11. In the example of FIG. 3, a second thermostatic valve 54 is illustrated. The second thermostatic valve 54 makes it possible to add a level of security to the system in order to avoid that the user at the end of the line does not receive water that is too hot if the heat recovery system is very efficient, thus meeting the norms set for the production of domestic hot water. The system of FIG. 4 represents another embodiment of the invention. It is another manner of using the device 7.

[0057] According to the example of FIG. 4, the system differs from that of FIG. 3 in that it also comprises a second device 7b intercalated between the storage cylinder 3 and an energy input device 82, said device making it possible to heat the water present in the storage cylinder 3. A device 7b coupled to a circulator 83 is thus used.

[0058] In this case, it is the circulator 83 that is going to be electrically connected and is going to set in motion the turbine 71b and the circulator 72b of the device 7b. This is going to induce a circulation of the fluid 81 (which turns in loop) which, when it is set in motion, will go through the exchanger 21b and the turbine 71b thus causing a simultaneous setting in motion of the fluid 41 through the circulator 72b. The fluid 41 passes into the plate exchanger 21b where it exchanges a heat flux with the water 81 coming from the energy input device 82. The device 7b enables the setting in motion of these fluids. In the example of FIG. 4, the device 7 of FIG. 3 continues to fulfil its function as described in FIG. 3. In an alternative embodiment, not represented, it is entirely possible to envisage only using a single device 7, either as illustrated in FIG. 3 or only between the storage cylinder 3 and the energy input device 82. The interest is only using a single command that is given to the circulator 83 to make the system functional. The energy, according to this alternative embodiment, which is going to set in motion the device, comes from the circulator 83, whereas in the example of FIG. 3, the energy comes from the pressure of the working fluid 1.

[0059] An estimation of the head loss induced by the turbine on the drinking water network as a function of the power required for the circulation of water in the plate exchanger is described hereafter.

[0060] The power of the circulator is defined as the product of the flow rate multiplied by the manometric head obtained on the operating curve of the circulator:

Pcirculator(W)=Flow rate(m.sup.3/s)P_exchanger_circuit (Pa).From equation 1:

[0061] The maximum efficiency of a Kaplan turbine is comprised between 84 and 90% with a minimum flow rate that can be turbined of 30% of the maximum flow rate Qmax.

[0062] The relative efficiency of the turbine compared to the maximum efficiency is greater than 80% when the ratio of the flow rates Q/Qmax is greater than 30% and is greater than 90% when the ratio Q/Qmax is greater than 40%.

[0063] The mechanical power of the turbine is expressed as follows: Pmechanical=efficiency_turbineP_hydraulic, where P_hydraulic=Flow rate (Q)Hnrho_waterg, with Hn=net available head, or head loss induced by the turbine, rho_water is the specific gravity of water, and g is the acceleration due to gravity.

[0064] Hence the expression of Hn:

[00001]$H_n=\frac{P_{\mathrm{mechanical}.Math..Math.\mathrm{turbine}}}{{}_{\mathrm{turbine}}.Math.\stackrel{.}{Q}.Math.{}_{\mathrm{water}}.Math.g}=\frac{P_{\mathrm{circulator}}}{{}_{\mathrm{circulator}}.Math.{}_{\mathrm{turbine}}.Math.\stackrel{.}{Q}.Math.{}_{\mathrm{water}}.Math.g}$$H_n=\frac{.Math..Math.P_{\mathrm{exchanger}.Math..Math.\mathrm{circuit}}.Math.}{{}_{\mathrm{circulator}}.Math.{}_{\mathrm{turbine}}.Math.{}_{\mathrm{water}}.Math.g}$

[0065] In the expression of H.sub.n, P.sub.exchanger circuit is in general a function of the circulating flow rate. The efficiency is specific to the dimensioning of the system and relative to the flow rate to ensure an equality of the flow rate of the fluids passing through the exchanger.

[0066] Let us take the example of a private house:

[0067] Maximum DHW flow rate of 10 l/min, i.e. 0.17 kg/s or instead 600 l/h.

[0068] Exchanger: thermal power exchanged of the order of 6-10 kW with head losses less than 1 mCE i.e. 10000 Pa.

[0069] The power required at the level of the circulator is P_mech_circulator=0.17 10.sup.3. 10000=1.7 W.

[0070] The hydraulic power coming from the turbine must then be P hydro_turbine=Pmech_turbine/efficiency_turbine.

[0071] Hence Hn=1.7/(0.8. 0.3 0.17 10.sup.3. 10)=4.16 m of water column is equivalent to 0.4 bars of pressure drop on the water column.

[0072] Hn must correspond to the head losses generated by the turbine, this signifies that there is an additive pressure loss on the water network of 0.4 bars for a flow rate of 10 l/min and a hydraulic resistance in the plate exchanger of 10000 Pa. This result is to be compared with the head losses of the other elements of the circuit and with the pressure of the drinking water network (generally comprised between 3 and 6 bars). NB: for network pressures greater than 3.5 bars, it is in general preferable to add a pressure reducer. Consequently, as a general rule, the pressure drop generated by the turbine should not exceed 10% of the total pressure.

[0073] In this calculation, the hydraulic/mechanical conversion efficiency of the turbine is taken around 30% with regard to the specific configuration with low flow rates.

[0074] The invention is not limited to the embodiments described previously with reference to the figures and alternative embodiments could be envisaged without going beyond the scope of the invention.